Receiving system for compressional waves



1927' H. e DORSEY RECEIVING SYSTEM FOR CQMPRESSIONAL WAVES Original Filed June 22. 1918 '1 $heets-Sh'eet 1 I nan" I "vi 5mm? HIS ATTORNEY April 19, 1927.

H. G. DORSEY RECEIVING SYSTEM OR COMPRESSIONAL WAVES Original Filed June 2 2, 1918 7 sheets-sheet 2' INVENTOR HIS ATTORNEY April 19, 1927.

H. e. DORS EY RECEIVING SYSTEM FOR COMPRESSIONAL WAVES Original Filed June 2 1918 7 Sheets-Sheet 4 III/17 hem ' HIS ATTORNEY April 19.1927.

H. e. DORSEYY RECEIQVING SYSTEM FOR COMPRESSIONAL WAVES Original Filed June 22. 1918 'r Sheets-Sheet 5 INVEN TOR WITNESS HIS ATTORNEY April 19, 1927.

H. e. DQRSEY RECEIVING SYSTEM FOR COMPRESSIONAL WAVES Original Filed June 22. 1918 7 Sheets-Sheet 6 5.558%. l 4. mm s. 2. 53:4

was": 'maasn d0 30 mmwv a Ev 3% Ev w im 773% WITNESSES ms ATTORNEY 1,625,245 Aprll 19,1927. H'sDoRsEY I RECEIVING SYSTEM FOR COMPRESSIONAL WAVES 'Original Filed June 22. 1918 7 Shet-Sheet v IAN/EN TOR WI Til/E88 His ATTORNEY- MWM Patented Apr. 19, 19 27.

"UNITED s-TATEs P-AT ENT OFFICE.

HERBERT onovn DOR'S/EY,.OI cmucns'rnn, mnssno n usn'r'rs, ASSIGNOB '170 JOHN" HAYS muom), 1a., or onoucnsmn, mssncnusms.

nncnrvmo' svs'rnn "i on comrnnssroiun wlvns 7 Application filed I'm 22,1918, aerating 15sec; Renewed .J;une 20, 1925.

Some of the objects of this invention are to provide a selective receiver jfor'compres sional waves which will be'sensitive' to waves of a given frequency but littlenfl'ectedby B waves of any otheriirequeney. or b irregular compressional vibrations'such as produce IlOl-SBS; to providelan improved recelverior' compressional submarine waves"; ,to provide in a receiver for compressional waves means *1 for automatically co 1Eensnt1ng for variations in the wave lengt "ofl th'ewavesowmg to temperature: ha ngesggto' provide 1n are ceivcrjf' for c'ompress1onal-j-- vaves means for amplifying the eti'ectof thewaves receivedand to provide :othe'rliinprovements as will "appear hereinafter. I Q

' In th'eaccompahyingdrawings, Fig. 1 1s 'a side elevation"-"0fi a-fmove-ble submarine sound receiVer i constructed in accordance with this invention; 'Fig." 2a v ew-of the some Fig.3 is airear elevation oft-heter- -,pedo' shown injF- ig; Flgs. 4"to-8 are enlarged transverse sectional .vlewsof the same taken on the lines4'.j4 to -8 respectively of Fig. 2; Fig. 9 is an enlargedfragmentar'y central longitudinal section of a portion of *Fig. 1,'the sectionyof the I being on line 9- 9 of Fig. 12' F1g. 10 1s a section on theline 10-.10 of Fig. 9; Fig.

9 as viewed. in thedrawings; Fi is an elevation of the right endof- 5 1g,;';9 as e i h e hg ;.F?"af131 fragn e'ryj longi ud a e ml fiiegqne f a mod'fied formIofsound receiveruconstructed in accordance with this in ent g F a fragmentary transverse section on' lme I partlyfjin vertical central-section "of a "further modified form of sound receiver constructed in accordance with this invention;.

Fig". 15 is ai fragmentary' side elevation 11 e sect-ionion the line. 1 7-.17 of Flg. 15 {looking-in the direction. of the-arrows; F1g;-

ggl sectionot a fui'therqmodiiied. form of sound receiver constructedin accordance v,Y lith. ."this, invention F 5- l9 pie-fragmentary righthand portion 11 is an elevation of the left end of Fig. v

Fig. 13 Fig; fii a side elevation modified form of sound'receiver constructed 'inaccordance with this invent on; F1g..16

side elevation of a marine vessel having a rudder provided with a submarine sound receiver constructed in accordance with this invention; Fig. 20 a diagrammatic represen-' tation of receiving circuits forming a portionfof this invention; Figs. 21 and 22 are R diagrams explanatory of the operation of the receiving system shown in Fig. 20 under different conditions of adjustment; Fig. 23

is a diagrammatic fragmentary to v ew ofa marine vessel provided with apparetus constructed in accordance with this plan invention; and Fig. 24 a fragmentary side elevation partly in section of a modified form of valve employed in this invention.

.. In Figs l to 12 is shown one, form of receiver for compressional waves constructcd in Iaccordance with this invention and adapted to be towed throu h the water by any "suitable marine vesse and to be. maintained at a substantially predetermined depth in the water toreceive submarine sound waves or other submarine compresisional waves and to control apparatus upon the vessel bvwhmhthe rece ving device is being towed; This form of the invention includes'ia trailer 49 havin a rigid body poi tion 50 which is preferab y made ofjhard buoyant-wood, or any other suitable m'nterial and "vt'hich has a stream line contour approximate the to rm of a fish. This body portion :50 is preferably substantially circular in"c ross-sect1on throughout the major portionfof its-length and is t-apered in opposite directions from a'plane perpendi'culnr to its 'flongitudinal axis and located nbout one fourth of the length ofthe body I portion from the front end of the body por- 'tion. The front end of the body ortion is pointed to pe mit the trailerto e drawn easily through 'the'water, and Hg rear end of the bodyportion isprovided ith a flat hollow metal blade'on'tail55 rigidwith the body iportion and arran ged 'suhstantially a plane containing the longitudinal axis of.

the body portion 50. The forward-portion of this'teil is tapered forwardly in thick ness and the tail .terminatesat its front end in sharp edges 57 to avoid resistance'wh'en t he-ifish is being drawn throu h the water. flfhe rear. portion, 013 the tai 55. is also ftaperedfreaigwfardiyfin thickness and the tail .-terminntes :n't its remr\ 'end in a shat vertiportion '50 is also provided with a nor mally substantially horizontal substantially fiat relatively thin metal blade or' plate 56 in the rear portion of the tail 55.

which projects equally upon opposite sides of the normallyvertical tail 55 and which is rigidly secured thereto and to the body portion and lies substantially in a plane containing the longitudinal axis of the body portion 50. The rear portion of this blade 56 fits snugly in a slot 60 provided therefor The opposite sides of the blade 56 are fitted to the contour of the tail and are rigidly secured to the tail by any suitable means, as forinst-ance by soft solder. The front inner portions of the tail 58 and of the blade 56 fit snugly in longitudinal slots provided therefor. in the body portion of the fish 50 and are held fixedly therein by any suitable means, as for instance, by pins or screws 60, and the front ends of the blade 56 are sharpened to avoid resistance when the traile-ris being towed through the water. Inthe forward lower portion of the trailer 49 is arranged a weight or keel 61 of lead or other suitable material which 1s so pro-- portioned as to balance the trailer in such a manner that it will float in the. water 1n a nearly horizontal position or with the front end of the trailer slightly elevated so as" to keep the tail 55 of the trailer slightly below the surface of the water so that signals may be received when the trailer is stationary, as will appear hereinafter.

For maintaining the trailer 49 at a predetermined depth while it is being towed a given rate through the water, two diving planes 65 are arranged upon-opposite sides of the trailer and in the same lane. These two diving planes 65 are rigi ly secured to the opposite ends of a cylindrical shaft 66 which extends snugly but rotatably through the trailer. These two during planes 65 are arranged in close proximity'to the trailer and the outer edges of these planes are curved forwardly and inwardly, and the front ends of these planes are arran ed to oscillate in slight segmental recesses 6 pro.- vided therefor in the side walls of the trailer so that the planes will not become enta led in seaweeds or other obstructions. Rigidly secured to the shaft 66 is a worm gear 68 which is engaged by a normally vertical worm 69 which is held against longitudinal movement but which is arranged to rotate about an axis fixed with respect to the fish. This worm .69 is provided with a downward projecting stem 70 rigid. therewith and than terminates at its lower end in a head -7lPQVid8d with a slot. arranged to receiye ascrew driver for rotating the worm" 69,- 7Ibeing arranged in a recess provided'threfor 1n the lower surface of the rei tgs thatths-l wer surf cffth he ffisflush with' he'lo'wer surface of the trailer.-

amen 90I- d' may .50 9f he t iler- By rotating the worm 69 manually 'in either direction the diving planes65 may be ad just-ed to any desired inclination with respect to thetrailer, and the worm 69 will hold the planes 65 against rotation under the action of the water while the trailer is being towed. The inclination at which the planes '65 should be adjusted will depend upon the depth at which it is desired to maintain the trailer and also upon the speed at which it is to be towed and the length and inclination of the towing cable. The

head .or'forward end of the trailer 49 may be prot'ided with two or more sharp edged fins rigidly secured thereto for deflecting to one side or cutting any obstruction which may be met.

For receiving submarine compressional waves, the tail 55 of the trailer 49 is pro- .vided with a circular aperture 80 which is closed at its opposite ends respectively by vtwo circular, parallel, coaxial diaphragms 81, which for clearness of description may be designated the primary diaphragms. These two diaphragms are of the same diameter and thickness and are preferably made of'hard. non-corrosivmmetal, for instance of hard rolled sheet brass, or other suitable materiahand should be of uniform thickness and free from kinks or bends to secure the best results. The marginal portlons of these diaphragmsare fitted snugly in two annular recesses {82' provided there.- for. in the opposite sided of the tail 55 and are secured in the recesses by any suitable means, as for instance by soft solder, the

cal planes spaced equally [upon opposite sides of the longitudinal axis of the body portion 50 of the trailer 49 but the diaphragms might be arranged in normally horizontal of the longit rdinal axis of the. only portion In the form. shown the, primary dia- 1.15

phragms 81 are arranged in normally vertiplanes spaced-equally upon. opposite sides 5O, by ha g g he -r angenmt of t e l .55. and the blade 56 by rotating these two parts with respect to the body of the trailer ab ut w si u ifiu iinn axis the e imai lien securing thesetwo parts in xedfposlnen wi h r pe t is th Leading inwardly ima-trades-reseaphrag'ins i electrical'oscillator 105 is nut: 80 and spaced\ between, the diaphragms 81 are twooppositely arranged openings 90 which lead' into an elongated opening 91 which is oblong in transverse section and which extends inwardly throiwh the tail 55.

The upper and lower walls 0: this opening 91-conver 'e inwardly and'its side walls" diverge slig tly inwardly, and thewalls of the oblong opening 91 merge into the walls 1 of an o ening 92'wli'ich is approximately elli tica in transverse section and which exten s inwardlyand gradually changes in transverse sectional contour until it assumes a substantially circular form 93in transverse sectional; a point where the central portion of the tail oins the body portion of the';-trailer At thief-point the circular 'o'pening 93communicates with a cylindrical opening-94 which extends longitudinally and I axia'llyvthroughithe rear portion of thebody' 106v is a cylindrical annular supporter par tition 107'made of brass or any other suitable. material and provided upon its outer end with an. annular marginal flange 108.

I This-support 107 is held in'a fixed position with respect to the casing 106-by meansof a set screw 109, the head of which is covered with solder to keep the casing 106 watertight. Seated. upbn the flange 108 is a secondary die. hragm 110 made of hard sheet f brass or ot er suitable material. The marg'inahportion of this diaphra m'is secured to-the flange 108 by anysuita ble means, as for instance by solder. The diaphragm 110,

p p is thus arranged in a plane perpendicular to the longitudinal ,axis of the casing 106. The

front face of the diaphragm 110 is provided with an annular recess 111 concentric there with, and the diaphragm 110 .is made of such a thickness and of such a free or vibrating diameter that the diaphragm when vibrating aloue will have a natural. frequency of vibration slightly higher than the natural frequency of vibration of the primary "diaphragms 81 and such that when the secondi ary diaphragm is actuating its oscillator, as

will appear hereinaftenthe secondary dia- 11mm with the part or parts carried therey will have the same natural frequency of vibration .as the primary diaphragins 81 r when these are in operation. a

Extending -inwaidly from the secondary diaphragm 110 is a soft iron cylindrical plunger 115 which is: arranged coaxially with theeasing 106 and which isprovided as ith a reducedthreade stem 11f; "which is inwardly through the support.

threaded through the central portion of the diaphragm 110 and clamps the plunger 115 against the inner surfaceot the diaphragm.

and in a fixedposition with respect to the .1

diaphragm. A nut 118 is threaded around the stem 116 and clamped against-the outer.

holding the plunger 115 clamped in position against the diaphragm 110. By changing the. thickness *of this nut the natural freside of the diaphragm, and assists in" qiiency'of vibration of the secondary diuphrag'in with its attached parts while in o 'emumi may be varied;

For-producing a permanent magnetic :field around the plunger 115, a permanently hollow 'cylindrical hard steel permanently magnetized shell -.120. surrounds and is coaxial with the plunger and fits sungly' in a cylindrical recess provided therefon iv the sup ort 107," and is held in position therein y a set screw 122 which is threaded The inner end of the shellis closed by a soft iron cap so a 125 which is rigidly secured to the shell by means of screws 126. Arranged within the shell and in longitudinal ali-n'ement with the plunger 115 is a cylindrical soft iron corei130, the inner end 'of'which is spaced and the OuterJend of which is threaded through the central ortion of the cap and is held in a fixe position with respect to the cap 125 by means of a lock nut 131.

Fitting snugly withinfthes'hell 120 and spaced from and insulated from the plunger ll5yandthe core is a coil 1'32 of insuand are insulated from the cap 125'. I

The inner'endof the casing 106 is her-' slightly from the inner end of the plunger 'latedwire, the o posite' ends 133 and 134 of which extendt rough metically sealed by means of a cylindrical closure 135 made of brass or other suitable material which fits snugly within the. casing and which-' is p'lqvided with-an outwardly extending cylindrical. flange 136 integral therewith. Tlid'oi'itefedge .of this ilan'ge 136 is flush with the in'ner'edge of the casing 106 and thetw'o edgesarie joined by an ann'ula'ncoating l3'l'of-"solder, thus hermeticallff's ealing the casing 106. If it should e filing; away the annular coating 137 of solder and then iwithdrawing the closure 13 5. The opposite'insulated ends 133 and 134 of the coil 132-are brought together in the form o'fa cable 140 which extends} tightly through a section of heavy soft rubber tubular insulation 141. which fits snugly in e k a hollow cylindrical bushing142 of brass necessary to reopen the casing 106 thiscohldbe quickly accomplished by or othersuitable material which fits tightly in a cylindrical opening provided; therefor in the closure 135, the bushing 142 being soldered or otherwise secured .in position in such a m uiler'ais to term. an a g j 'l'he bushing 142 and is clamped securely Y against the bushing 142 and around the cable 140 bythe cap 143 in such a manner as to provlde a. mechanicallystrong and water-tight joint. The inner end of the cable 140 and all soldered joints are covered -with a coating of shellac varnish, as a further precaution against leakage of air, water, or electric current, and to avoid cor- 'rosion. The cable 140 is extended through and secured against longitudinal movement in an axial cylindrical opemng145 extending longitudinally through theb'ody of the trailer, and the cable 140 is extended forwardly from the trailer through any desired distance to serve as a tow line and also to conduct the electrical oscillations produced in the coil 132, as will appear hereinafter.

-At the pointfwhere the cable 140 merges from the body 50, a heavy spiral spring 146 is wound snugly around the cable and its.

surroun mg the air column 150 were exinneriend is rigidly secured-in a recess provided theretor in the front end of the body 50, as shown in Fig. 2,-so that in towing or air as water from enterin through the bushing "151.

handling the trailer the spiral 'springwill prevent any sharp bends in the portion of the-cable surrounded by the spring and thus avoid injury to the insulation of the cable.

. For testing for leaks and for controlling the pneumatic pressure within the air space 150 betwen .the partition or support 107 and the closure 135, a checkvalveis provided.

This valve comprises a hollow c lindrical brass bushing 151 which exten' s tightly through a cylindrical opening provided therefor in the closure 135 and soldered in position to make a tight joint. Extending through this bushing 151 is an. inwardly opening valve element 152 which is normally held closed by a compressed spiral. "spring 153. A cap 154 is threaded over the outer end ofthe bushing 151 and normally acts to clam a rubber washer 155 over the outerlend o; the bushing toprevent either the. space 150 removing the cap 154 and washer 1.55 and attaching the delivery pipe of an ai-rpurn'p to the outer end of the bushing 151 any desired pressure of air may beapplied in the .s' ace 149.

Under some conditions it may be ound desirable to'have the pressure in the space 149 slightly above atmospheric pressure, or even 'sjuflicient to balance the water pressure at the depth to which the device ay be submerged wheuin operation. It been dably in t e casing 106 and which is held found that when'the receiver is scaled up at a temperature above the working temperature t is desirable to have the air in the space 149 slightly above the atmospheric pressure at the time of sealing.

The secondary diaphragm 110 is'spa'ced at such a distance from the two primary diaphragms 81-.8l' that the column of air 150 enclosed within the trailer between the secondary diaphragm 110 and the two primary diaphragms 81 will have a natural frequency of vibration equal to the natural frequency of vibration'of the diaphragms when the temperature of the water surrounding the trailer 49 would cause changes in the tuning of the column of air 150 unless the Walls, inoludin the diaphragms 81, 81 and 110,

panded or contractedby vsuch changes in temperature sufiiciently toovary the proportions of the air column 150 sufficiently to compensate for such changes.

' It has been found that in the construction shown in Figsjl to 12 and just described the expansion or contraction of the walls surrounding the air column 150, due to changes in the temperature of the surrounding water, is not sufficient to compensate for I such changes to such an extent as to maintain a constant tuningof the air column 150, under such variations in the temperature of the surrounding water as 000,111 in practice in diflereut localities and at different seasons of the year, and consequently this invention provides means for aut matically keeping the air 0011111111350 tuned to a constant frequency.

In Figs. 9 and 10 is shown a device constructed and arranged in accordance with this invention for automatically keeping the air column 150 tuned to a constant frequency under variations. in the temperature of the air column. This device comprises a cylindrical support 170 which fitssnng'l'y but in a uitable fi Po t n betwe n the .ri-. mary diaphragms 81 and the .sewndary diaph agm 1 0 by mea s at a he d d screw 171 x end ng oose y t e ghfthe easing L0 and thre ded into the support 170; The he d of h 'wrew 1.71 is veregl with solder to avoid leakage of .air or Witter through I the o ninlg throu h which the "screw is 'the resonator will be rendered responsive rran e within the support 170 an extending iametrically thereof: is' a shaft 172 the ends of which are conical and mounted for oscillation in two conical recesses provided thereto! 'in two bearings 173 and'174, one of which, 173, fits tightl in an internal recess provided. therefor in t e sup-' port 170 and the other of which, 174, is threaded tightly through the sup rt. 170 and'is provide u n its outer en 'diametrical slot 1 5, arranged to receive a screw driver'for adjusting the position of the bearing.. Ri idly secured to' the fshaft; 172 is afiat circu ardisk 176 of sheet metal forming a butterfly 'valve' which is ably so arranged that its-center is int elonrefergitudi-nal axis of the casinglOG.

-For automatically swinging or. oscillating the disk or valve 176- in response to variations in the temperatureof the air column a crank arm 180 is mounted upon and is rota-tively adjustable with respect to the shaft 172, being normally held'fixed with respect to the shaft by meansof a set screw 181. This crank arm 180 is p'rovided with.

= an elongated slot- 182 extending radially with respectto the shaft 172 and in this'slotis arranged a bolt 183 rovided' with a-collar 184 and a nut 185 w ereby the bolt adjustablyv clamped in position. One end of the 'bolt is extended to form a pivot or crank pin 186 and snugly but rotatively surround- (pin' is one end of a pit-man 187 against movement longituingthe crank which is hel clinallyof the crank pin 18 6 in onedirection "by means of a washer 188 and a nut. 189.

' The other end of the pitman 187 is,pivotally connected toone end of abimetallic expansion member 190 the other end ofwhich is. rigidly connected toa rigid bracket .191 which 'isrigidly secured to the su port/170.

The expansion member 190 "inc ud'es two" arms' 192 and 193,.one end'of which is securely riveted to a correspondin end of the other. "Each of these arms is Formed of two leaves or layersof different metals or other material having diflerent coefficients of linear expansion due to heat." For instance each arm maybe made of a layer 195 of-iron' and a layer 196 of brass, clamped together by rivets 197, the more'expansive. material being arranged upon the same side of each arm so that any decreasein the temperature of the air column 159' will cause the valve 176 to be rotated in a clockwise direction as viewed in Fig. 10. l It is well. knownamong experts 1niacousties that if the mouth of anopefn resonator be contracted the pitch"o f-.the"res'onator will helowered', or i'n othe'r word's'the "resonator" will be rendered responsive to a longer-wave length, and .converselyl that ifthe mouth of 1 Ithe resonator-beenlarged; the pitch of the .reso'nator. willbe raised, "ior i'n. 5 other yards with-a r in Fi 1 to 12, which is closed at both ends to'ashorter wave length. v The length of an ordinary open resonator is approximately equal .toione quarter of the wave length of 7 the sound waves to which-theresonator will respond, and the length of an ordinary resonator which is closed at both ends is equal approximatelyto one-half the wave length of the sound waves to which the resonator will respond.

The actual-length of the resonator shown and w ich encloses the air column 150, is the distance. between .the --secondary diaphragm 110 and the'extreme outer. ortion of the cylindrical wall which boun s the aperture 80 which is closed by the. primary dia-.

wave length from the secondary diaphragm 110, since this portion of the resonator is cylindrical, and its exact position may be readily-found by any of-the well known methods given in text books on sound.-

In the operation of the automatic temperature compensating device shown in Figs. 9 and 10 the parts are so adjusted, initially,

that when the air column 1504s at the highest temperature under which the trailer will ever be used, thegvalve 176 ,will be. in a plane perpendicular to the longitudinal axis of the casing 106 and approximatelycoinciding with the plane containing the crests of the half waves set up in the resonator when the resonator is in operation. f This will be the proper adjustment of the valve for the longest wave length of the resonator. I

Then forany lower temperature the expansive member 190 will act to automatically rotate the valve in a counter clockwisedirection as viewed inFig. 9 to diminish the effective' area of the valve accordingly and to correspondingly increase the effectivearea of theopening at the'orestS of the half waves between the; opposite ends ofsthe resonator .have been '-correspondinglyshortened by the decrease in temperature.

When'the trailer 49 shown in Figs. 1' to 12'is in operation receiving submarine-compressional or sound waves havin a fre quen'cyapproximately equal to the requen'cy to'whichi the primary diaphragms 81,- the aircolumn *150 and the secondary diaphragm 110' are tuned, the primary diaphragmsSl are vibrated by and in unison with thereceived waves and setup corresponding vicompressional gvaves produced in-the air ;col

of the resonator. These vibrations of the "air column 150 'act to amplify the vibrations of tlie, primary diaphragms 81 and to setup corresponding vibrations in the secondary diaphragm 110" and the soft iron plunger 115; carriedthereby. The vibrations of the plunger 115 act inductively in a well known manner upon the fixed soft iron core 130 and upon; the'coil 132. to cause correspondlng electrical oscillations to beset up in the coil 132 and consequent-lyin the circuit 133-134 controlled bythe coil.

In this operation-the an column 150 forms a perfectly elastic connection between the 5 slight and would not appreciably change the.

normal presslu'e of the air column 150.

By thus connecting the "rimary diaphragms 81 to the secondary diaphragm 110 through an air column 150 itis possible to V make the primary diaphragms 81 of "relatively large diameter so as to have largereceiv'lng surfaces, and tomake the secondary diaphragm 110 ofrelatively small'diameter' T and consequently extremely sensitive to the umn 150 by t e primary diaphragms. -By

this arrangement vibrations of the two pri mary diaphragms" 81 of slight amplitude produce corresponding vibrations of a greater amplitude. in the secondary diaphragm 310. .Moreover vby making te sec ondary. diaphragm 110 and the electrical oscillator actuated thereby comparatively small, these arts maybe made with, great accuracy an of extremely light weightthus increasing'the sensitiveneis, efiiciency and ef.-.

. .r In Fig. 1.3 isshown atmodified formofrefectivenessi of these parts 7 ceiver constructed in accordancewith this.

invention for receiving compressional-waves.

This receiver comprises a rigid. cylindrical casing200-whic'lr 1s provided with "terminal annular outwardly projecting flat flanges 201 and 202. .Rlgidly securedto theouter end of the casing 200 an coaxial therewith is a flat circularhrigid plate .205 which is provided'with acentral circular opening 206;

and which is provided upon, its outer v flat surfacewith'an annlular groove concentric therewith and shape in cross section; spacedg'slightlytin (front ofthe plate 205 and arranged coax'ially therewith and. substantially parallel thereto is aflat rigid circular plate 2'10which is provided with a central circular aperture 211 and which is brations or half waves in the air column 150 depth.

:-also provided upon its inner surface with-an annular groove 211' V-shapein cross section and arranged oppositethe annular groove 207'. of the inner plate 205. Seated in the two grooves 207 and 211 is an'annular gasket 212 of rubber which normally holds -the plates 205 and 210 slightly spaced apart.

The outer'plate 210 is secured in a substantially fixed position-Witlrrespect to the innerplate 205 by means of screws 215 which clamp the outert plate securely against the.

gasket 212, and the gasket th-us clamped acts to preventany leakage of air or water. be-' tween the plates.

The front surface of the outer plate 210 is provided with a conical recess 216 coaxialtherewith, and covering this recess and coaxialtherewitll is a vibratory primary diaphragm 220 made of hard rolled brass or of any other hard non-corrosive metal or of any other suitable material. The marginal portion of-this diaphragm is rigidly secured tothe outer plate 210 by any suitable means as for instance bysolder. The plate 210 may be recessed to receive the marginal portion ofthe diaphragm 220 in the same manner that the tail'85 is recessed to receive .the diaphragm 81 in the construction shown in Fig. 4. A short screw 221 may be threadedthrough the central portion of the diaphragm to receive a nut 222 of a suitable bration. By changing the nut 222 for one thicker or thinner the principal natural frequency ofvibrationof the diaphragm may be varied accordingly and the diaphragm weight to cause the diaphragm thus loaded to ave the desired natural frequency of viinay" thus be tuned to respond to any desired frequency of compressional waves when the dia'phra m is immersed in water at a given he inner end of the casing 206 is scaled by a flat rigid circular metal plate 223* rigidly securedther'eto by any suitable means, for instance by solder. For receiving and amplifying the compressional waves produced by the action of the inner'surface of the primary diaphragm ZQU When-the' diaphragm is vibrated by the action of compressional waves upon the out-- .er surface of the diaphra m, a resonator 225 is providedwhich inclu es two longitudi-- nally aline'd spaced cylindrical tube 226 and within thecasing'200 and coaxially therewith.) These tubes are made of brass or any other suitable metal" or materiaL and yieldingly connected together by a sleeve 230- of fe to hold the tWO' tubes in'alinement and to tube 226 to the inner itube 227;

The tubes 226 and 227 are spaced apart 227 of the same diameter which are a ranged tor other sound absorbing material which fits tightly arqund the two adjacent ends of the two tubes 226 and227' and which servesprevent' any extraneous noises from being transmitted through the metal of the outer preettti ffalea a region that lies a are crest'of' the half waves that are set up in V theresonator when in" operation, as will a pear hereinafter, and consequently the fe t sleeve may be provided with a series of aperturcs 231 a 'rangedbetw'een the tubes to prevent a node from being formed in this region and consequently to prevent the resonator from responding to the first overtone of its fundamental note. The outer end "of the outer tube 226 fits tightly inand is 'ri' 'dly,

" secured in the aperture 211 provided -t ere- I for in the outer front late210, and the inner end of the inner tu the backplate 223.

27 s sip ed w f-Bjoth tubes 226 and- 227; are furthersecured in position by" means of a loose cotton or othersuitable packing 235 which fills the annular space between the tubes and the outer casin 200 and'the space between the inner end 0 the inner tube 227. and the-back plate 223. The cotton packing 235 serves notonly as an additional support for the tubes 226 and 227, but also prevents the enclosed space around thetubes from acting as a resonator, and serves to insulate both tubes :from an extraneous noise or soundsthat might otherwise be transmitted to the tubes 1 through the enclosed space surrounding the tubes. g From the foregoing it is evident that in this construction the inner tube 227 of the a resonator 'is entirely supported through the .joint action of the felt sleeve 230 and the loose cotton acking 235 and consequently is entirely insu ated from all extraneous. vibration's except such as are transmitted through the primary diaphragm 220 andithe space surrounded bythe outer tube'226. t g I .For receiving the compressional waves set up inthe resonator 225, and for transforming the waves into electrical oscillations, a' sound actuated electrical oscillator 250 is 1 provided which; may be of any suitable construction but which in the form shown in F 13 includes a hollow cylindrical metal bushing 251 which fits tightly but adjustably in the rear portion of the inner tube 227 and which is provided with an internal annular flange 252 integral therewith spaced slightly back from the front end of the bushing. The front end of the bushing 251 is covered by a'circular secondary diaphragm 255 of brass or any other suitable-material which is marginally secured tothe bushing by any suitable; means, for instance by sol-' der. Thesecondary diaphragm-255 is spaced at such 'adistance from the; primary diay phragm 220 that the column of air enclosed (iii in the resonator 225between the twodiaphragms will have a natural frequency ;of vibration equal tothe naturalfreqiiency'of vibration of the primary diaphragm 220' when the device is in operation. This distance will be slightly than one halfthe 261 is made very small andthe rin wave length of the compressional waves to which theresonator will respond when thus 4 tuned.

Arranged upon the rear side of the-dia phragm and ooaxially with the inner tube. 227 is a cylindrical soft iron plunger 256 which has afreduced' front end 257 which fits tightly through an opening provided therefor in the central portion of the diaphragm and the plunger is clam ed securely to the diaphragm bymeanso a 'nut 258 plunger. thickness or additional nutsniay be threaded over the front end of the plunger to cause the diaphragm when thus loaded to have the same natural frequency of vibration as the primary diaphragin- 220 and the column of' air confined 1n the resonator225. An annu plunger to vibrate in any direction other than along the longitudinal axis ofthe inner tube 227. A'soft iron shell 260 fits tightly in the" bushing 251 and in the front end of this shell is fixedly secured a soft iron ring .261 the inner wall of which is spaced from the plunger 256.

I The annular air gap between 'the 'plunger256 and the inner wall of the ring 261 is made comparatively thick so that the magnetic reluctance of the air gap will be as small as possible. 4

The outer end of the shell 260 is closed by 4 262 of soft iron held in place a circular ca I b screws 26 Threaded centrally through t e cap 262 is a longitudinally adjustablecore'263 of soft iron which is locked in any desired position of adjustment by means of a nut. 264. The inner end of this core is:

spaced at all times from the inner end of the plunger 256.

threaded' over the reduced end of the This nut 258 maybe varied in and. thus minimize any tendency of the f Surrounding the core 262 and fixedin the shell 260 is a magnetizing coil 265 which is separated from-the core by a tubular section of insulation, the inner surface of which is spaced from the core. This magnetizing coil forms part of a circuit 266 which extends through and is insulated from the cap 262 and extends throu h and insulated from stufiing boxes 267 w ich extend through the back plate'223, andwhich are construct- .ed as hereinbefore described and as shown in Figs. 11 and 12. This circuit is arranged.

to be energized by a'battery 268 or other meet current.

source of v the plunger 256 and fixed Surroundin within-the she I 260 is a generating coil 270 which is separated from the lunger by a tubular section of insulation e inner surise' face of which is spaced from the plun er to allow free vibration of the plun er ongitudinally. 'Th-is coil forms part o v a circuit 271 which extends throughand is'insulated from the cap 262, and which extends through and is insulated from stufling boxes .272, constructed as hereinbefore described and extending through the back plate 223.

Fitting tightly within the shell 260 and arranged between and insulated from the two coils 265 and 270 is, a ring 275 of-soft iron which surrounds the inner end of thecore 263. The 1 two conductois 271, leading fgom the oppositeiendsof the generating coil 270 extend throiwh and are insi'ilatcd irointhisv ring 275. The innerdiameter of this ring 275iis soproportioned as to leave normally afslightly widerannular air gap between-the core 263=and the inner: wall of the ring than isleft between the rounding the plunger, and so that when the diaphragm moves outwardly thusincreasing. the air gap between the core andthe plunger the magnetic reluctance will be much less from the core 263 to the ring 275than from the core ,263 thronghthe plunger 256,-and consequently there will be a greater change in flux through the generating eoil 270 than there would be if the flux were'allowed to leak back to the shell 260 withoutpassing through the ring 275 surrounding thecore.

It is therefore evident that in this construction the intermediate ring 275 acts as an intermittent .or periodic magnetic shunt to increase the efliciency o f the oscillator.

The modified form of receiver shown in Fig. 13 may. alsobe provided with any suitable means for automatically keeping the air column enclosed "by the resonator 225. tuned to'a constant frequency under variations in the temperature of the air column. For instance, the receiver may be provided with a device for this purpose including a flat circular valve 280 carried by a rotary shaft 281 terminally supported in two bean ings 282, 283- threaded through two lugs 284:,

285 integral with a cylindrical sleeve or support 286 fitting snugly in the inner tube 226 and held in a suitable fixed position by a screw 287. In this construction the valve 280 is controlled by a bimetallic expansion member 290 acting through an adjustable these parts being substantially the same in construction and operation asfthe valve 176,

a longitudinally curved intermediate expansion member 190, pitnian .187 and crank arm 180 shown in Figs. 9 and '10, and liereinl'iefore described.

In Fig. let is shown a modified fornifot this invention arranged to project into the surrounding water through an exterior wall 3000i a marlnc vessel. ;.'lh1s,i "or1n ncl uh-rs a metal tube 301 whichextends snugly through asoitrubber \VtlSlll-l',,iiii)2 which [its snugly '111 a one ular; opening. provided therefor-in the wall 300. 1 Rigidly secured ito the outer endof the tube 3.01, is a, hollowcirculKL'Ji'IBttLl cas ng. 305 in whichjs marginally secured a circular, flat "prin iary "diaphragm 306 made of hard rolled lnrass ,or anyj'pthcr suztablematernal.--.The tube 301 is clamped ner end of the tube 301 is secured-an elemtrical oscillator 105' constructedalul. ar-

rangedas hereinbeiorc described and shown in Fig. 9, including a secondary diaphragm 110 which is tuned to the same natural frequency of vibration as the primary diaphragmand which is spaced from the primary diaphragm at such; a distance that the vc'olumn of air 310 enclosed between these diaphragms will be tuned-to oscillate in the same frequency. as the diaphragm. The pri- The washer 302 {acts to form.

.yieldingly in "position :by. zn' eansr of a nut 307 mary diaphragm306 may-be arranged with its outer surface in contact-with the water and e ther in a 'horlzontal or 1n a vertical plane, or m any other conven ent posit on.

'It. is thought that the operation ofthis form of the invention will be understood from the foregoing description. I 4

In Fig. 15 is shown a further modified form of this invention arranged to project into the surrounding water through an exterior wall 315 of a marinevessel. 1 This form includes a main metal tube 3-16 which is substantially I circular in cross-section throughout its length and which consists of two. substantially straight portions and a irtion.'the longitudinal axes of the-straight portions being arranged to form a right the" inner face of the washer 317'. 'The Y I washer 317 serves to "prevent leakage" of pitman 291 and an adj ustable-crank arm 292,.

water-T through the opening in which 'it is located anda'Tlso serves'to protect the tube "rial and of the same dimensions; The *outer secured to the 'out'ei' end of the tube'is a t oblong-metal plate 318 which is arin a plane containing the-longitudinal-axis of the outer portion of the tu 316 and substagtially perpendicular .to-the--lon-' gitudinal'a is of the inner-end of the tube 316, and which is .providedfiwith a circular opening 319 over which are marginally s e-- cured two parallel fcircul'ar; primary dia-- phragms 320, 32-1;;made ofthe same matesurfaces, of these diaphragm: 32,0;321 are I flush-with the outer mtacesof-th pme 318 he thin and 1s tapered in-thickness orwardly and rearwardlyfrom the diaphragms alongga line parallel to the wall -315'to form a sharp late 318 is made ffcom aratively longitudinally curvedfr'ont edge x322, and-a sharp" longitudinally curved-Irea'r edge 323, both edges being substantially in a plane substantially perpendicular .to the plane of the wall 315, and the rear edge being spaced at a greater distance from the'diaphragmssurrounds the tube and which fits snugly in a rigidcylindrical su port 322 which is .fixedlysecured to the we 1 3-15. The washer 321 protects the tubefrom' vibrations ofv the wall 315 of the" boat. In longitudinal alinement with the innerend ofthe tube 316and spaced slightly therefrom is an inner cyIindrical secondary metal tube 325 which ext ends through and is coaxial with a rigid annular support 326 -which is'fixedly se-' curedto' 'the wall 315.?" The secondary tube 325 is yieldingly hcld substantially in a given position-with r tl'to the annular support 326by meanso a plurality of continnons, normally slightly extended rubber 325 and. aroundthe en 00 around the tube of four relatively bands 327 which are 100 rigid bars 328 whiclr'are substantmll par- "iilIel'to the longitudinaljaxisofthetu 325 and which are rigidly secured to the annular support 326. The -rubber bands 327 protect theltube 325-'from"vibrations.-of the wall 315 of the boat. a suitable position as hereinbeiore" described and includin a "diaphragm 110, and arranged'to set up e cc:

Wifi-ical oscillations in a circuit '133134 which may be arranged to control any de-- sired receiving device or stem, as will appear hereinafter. The mam and se ondary tubes 316 and 325 are so arranged and proportioned that they form jointly a resothe-inner-endof the secondary tube 325 is an electrical oscillator'105. constructed nator which is tuned to the natural irequency of vibration of the diaphra 320 321, when the diaphragms are3su mer and 1n operation. The tubes316, 325 are spaced. apart-along a region which lies at.

the 'node of the half wave length which, when the device is" inoperation; is set up in. the' column of air enclosed by the tubes. In

this construction the distance measured along the longitudinal axes of the tubes half waves -which,- when thedevice is in o eration, are set up in the air column en-' -c osed by the tubes.

fron the outer 'end of 'the'main tube 316 to the inner end OfthG secondary tubelwould be approximately equal to the length of the- ,InFig. 18 is. shown a modified form of this invention. whereby compressional, subexterior shell or hull 330 ofa marine vessel. This form comprises a circular plate 331 of metal or other suitable material whiclirests marginally upon a soft rubber apnular gasket 332 coaxial therewith and which is interposed between the plate 331 and the exterior Wall 330 of the vessel. The plate a 331 is clamped against thegasket 332 by means of two or more clamps 333 held in position by screws 334 extending -loosely through the clamps and threaded into the exterior wall 330,'a soft rubber pad 335 .marine waves may be received through the being inter osed between each clamp and the plate. he plate 331 is provided with-a central aperture .inwhich is rigidly secured one end of a tube 336 of metal or other suitable material which is coaxial with the late 331 and which projects inwardly there rom.

In the inner end of this'tube 336 is-secu'red an electrical oscillator 105 which is -cons'tructed as hereinbefore described and which is arranged to set up'electrical oscillations] irra circuit 133; 134. The oscillator includes a diaphragm which is spaced at such a distance from the wall that the intervening column of air 337 enclosed by the tube 336 will be tuned to respond to the I same frequency of vibrations as the natural uency. of vibration of the diaphr 110. In the operation of this form of e i invention compressional submarine waves having the same frequenc frequency of vibration o the diaphragm 110 are transmitted through the; exterior as the natural wall 330 of the vessel and act to set up core responding vibrations in the column of an 337 and consequently in the secondary dia-- .phragm 110.- The vibration of the diaphragm 110 sets up corresponding electrical oscillations in the circuit 133, 134, as here,

inbefor'e described.

In Fig. 19 is shown a modified form of this invention in which a receiving device constructed .in accordance with this invention is arranged in a rudder 340 of a marine vessel 341-. This'torm of the invention inif) obvious that all of I eludesenelectrical osc-ilihilor 1tl5 which isenelosed in an opening provided therefor in the rudder 340 and which is arranged to set up electrical oscillations in the c-irc'uit 133, 1134 which may be arranged to control any 1,119 arranged to be actuated as aresult of the vibrstion of twq pal-ills], oppositely iii"- posed, spaced main diaphragrns 343. \vhic are marginally secured to the rud'der340 over a circular opening providedtheretor through the rudder andwhich are tuned to vthe same hatural frequency of vibrationes' the natural frequency oflvibr ation of the secondarydiaphragm 110. A column 344 of air isfenclosecl in the rudder between the. sec- 'ondnry cliaphregm 110. and the main dinphrafl'rms- 343 and is so proportioned as to tiesponil to the vibrations ot the main diaphragms 3453 when these are submerged and vibrating in their -t-ural frequency. It is he various features of the repeivingsystems hereinbefore described and, shown in Figs. 9 to 13 inclusive might be embodied in the form of this inventlon shown in Fig. 19.

I adjustment, the switch 411 may-then he Opened to avoid waste of current when itzis' 'not desired; til-operate the system, and the 3 system may afterwardsbeqnicklyrendered operative merely by closing the switch 411, whereupon within if few seconds the "blumentswill 'be broug-Eht to their steady, predetermined working temperature. r'lhe three j amplifiers are arranged. to be controlled by a circuit 430 which "may be for inst-once any one ,of'the hereinbefore dt'scribed ch'cnits 1331 134; or the =hereinbefore ilescribedcir cuit- 2"T1. 271, and which includes a 1uain in-. ductairce 431 and an auxiliary Inductance 432; The main inductance 431 'forms the terniined figequencyof the electrical osci llations om th'eeircuit 436).- This closed circuit 435 is arranged togcontrol the first amplifier.

.400; on'e'side of the variable condenser 4% being connected to the grid 407 of the amplificr through a sto-ppn-gecondenser 437 and the other side of the variable condenser 4315 bei'ngxconnected to the corresponding filament 406 throrrgh an extension of the math posit ve conducton412; of the battery 410.

ms For receiving end utilizing the electrical Thefirst amplifier 400 controls a circuitinoscillations produced 'as hereinhetore 'de' eluding a battery '0, an inductance 441,

scribed in the circuit 271 271 or in any of mild a portion of the main positive condncthe circuits 133134, this invention wprollO-B 412. This inductance 441 formsthe rides an improved receiving. system, one primary of-an antotransformer having a secform of which is shown in- Fig. 20. In the ondar'y inductance 442 which is in-nclosed form shown this systelii cdmprises three dehsci llatory circuit 443 including a variabletectors or amplifiers 400, 40.1 and 402, which condenser444. This circuit is tuned to the for clezirness of deseription'nmy be referred predetermined frequency of the'oscillati-ons to hereinafter as the first second, and third set up by the electrical oscille-tor in the cir- H' amplifiers -respectively. These amplifiers p'ruit 430, and is arranged to that through a maybe of any suitable constrilction 2nd instoppage -ehndenser 445 to control the secther fiorm shown are of a'. 'we"ll known coiionrl amplifier 401; struction, each comprisiittg a vacuizied glass "rlh-e second amp bulb 4015 containing afilnment or heater 406, in'clud-ing a better 450, and an inductance Y afgrid 40R, and aplate 408. iThe'three file-1 451 which 'forins te primary of an indie lifi'er 401 controls a.- circuil.

llU

merits. 406 are arranged tobe heated by 721) transformer. which has a secondarvindnc- I common battery L 10.: The positive pole of trance 452 which. is 'in'e closed"osciflntory eirthe-hattery 410 is connectedthrorugha switch. c nit 453 which includesa vairialile condenser 411, main positive conductor :12 and brdnchfi454. Thisilosed circuit is turned to the saimef conductors 412M421 nneieridi each filament, predeterminedfreqnencyas the other closed and the negative-pole of the'ba'ttery 410' is oscillatory circuits. 435 aFnd4 t3' and-isnrconmcte d through; abaitast-AM; main negaranged 10rd; through a stoppagecondenser tiive conductor 4-15, brimch conductors 416,- 455- tocontrol the 'third mpIifier-40'2'.

-'fil nment l06. i r ,The ballast 4214 -may: be of any suitable and rheostzits 417 with the otherendJ-bf. each construction andin the form shown includes an iron wire 41:9 arranged in a container- 420 i Bil hydrogen. gas,emd the; ballast 41 i 1s of such capacity that having once adjusted "ft lnenrlzieostats lgwithithe switch HI-closed, tom, 3 shuntcircuifi 470 extents around the I. toea nse the filament to be heated to .asuittelephone receiver, 463 from a point between The third amplifier 402leonirols a circuit I able temperhtnrgthe bellast 414 will cone the relay 462'iaud the receiver to the main 'cpenssite for airy fluctuations in :the voltage positivez-conductor 412 of the "l'retterv/41 0. ot the battery-410. Having once made this This shunt circuit includes e variable 'collinductance 432, forms the primary.

been found in practice that this shunt circuit 470 increases by many'times the sensibility 1 ream adjustably coupled to the hereinbefore described auxiliary. inductance 432 and forms the secondary of an adjustable coupling t1" ..sformer 473 of which the auxiliar coil t has of the system. 7 Now witha proper coupling of the electrical oscillator. 105- and the transformers 433 and 47 3 so'that all the currents will aid each other, and with a proper tuning of all the: ,closed oscillatory circuits, the system shown in Fig. will sing -or oscillate at the predetermined frequency. A By then decreasing the coupling of the transformer 473 by increasing thejdistancebetween the coils 432 and 472 until the system will oscillate only while oscillations of the, redetermined frequency are being. generate by the oscillator 105: in the circuit 430, 431, 432,. the

system will be ad 'usted to its'ma'xlmum-sen sibility and no urther adjustment will-be necessary. I

In Figs. 21 and 22qthe-full lines 475 and 476 indicate approximately the resonance curves of the system shown'in Fig. '20 when operating under difi'erentconditions. The frequency of the received compressional waves is plotted along-the line of abscissas 477 and the am litude orv amountof useful direct; current w ich is delivered through the a-mmeter 361 is plotted along the line of ordinates 478. The dottedline 479 indicates approximately the amount of current neoes saryto operate'the rela 462. In Fig 21 the resonance curve 475'in icates approximately the o eration of the system when thevibrat' 'ing e ements are not all tuned the'same frequency and in Fig. 22 theresonancecurve 476 indicates approximately-the operation of thesystem when the vibrating elements are all tuned to'the same-frequency. The depressed portions of the curve 475 'of-Fi 21 may bevery narrow, for instance on y the width resulting from a few cycles difi'erence in the frequency of the received 'com- .pressional waves. A comparison of the two resonance curves 47 5 and 476 makes itevident that inthe operation of the system sharpness of tuning, or selectivit sensitiveness, and efficiency are all great y increased by having the various elements-of the, system tuned-to respond to the same frequency.

InFig. 23 is shown a system constructed in accordance with-this invention whereby a primary trailer may .be. normally towed by a; vessel and a secondary trailer may be held n reserve and automatically .substitut ed for'the primary-trailer in case the primary trailer should become injured to such an 'extentas to short-circuit or breakthe circuit extendingthrouqh the cable by which the primary trailer isv eing towed. In the.

denser 471 and an matinee-472 which is form shown this system comprises a marine vessel or other movable body 500 provided with a primary trailer 501 and a secondary trailer 502. Thesev two trailers are constructed in any suitable manner, for instance .as hereinbefore described and shown in Figs.

1 to 10 except that the'primary trailer 501 contains as an additional feature a battery 503 the function of which will be described hereinafter. These trailers are arranged to be towed respectively and successively by two cables 505 and 506,'the outere'nds of .which are connected as hereinbefo're' described to the front ends of the two trailers respectively and, the inner ends of which are secured in fixed positions by clamps 530' and 531 to the vesse the two cablesf505 and 506 respectivelyare twocircuits 536, 537 and 538, 539,.each of which. corres nds to the hereinbeforedescribed circuit 133, 1.34, of the trailer 49 shown in Fig. 1, and eachof which is ar- 'ranged. as 'hereinb'efore describedto have set up I therein electrical oscillations of a predetermined frequency as'a result of the.

action of compresslonalsubmarine waves -of the same frequency actingu n the corre sponding trailer. 501 or 502. he added battery 503- of the primary trailer 501 is arranged in the circuit .536, 537 controlled by the priniarytrailen. This circuit'also cona. switch 557 is arranged to connect'theztwo terminals 555 and 556 either-with the two terminal contacts 550'and 551 of the circuit controlled-by the primary trailer 501,0r

Extending through The initial circuit 430;

hectt-wo fixed'ter male 555 and 556,.Hnd Y with the'two terminal-contacts 552.and 553 of the circuit trailer 502.

The primary trailer 501 is norma y @051- tioned in the water and is normall towed controlled by the secondary by the boat 500 whi-lethe secondary trailerport 559 which is rigidlv securethto the boat 502 is'normally heldimreserve upon a sup- 500 and which has a hollow semi-cylindrical upper surface the longitudinal axis of which is inclined rearwardly and downwardly at an angle sufficiently steep'to cause the secondary'trailer 502 to slide" downwardly into the water when released. The secondary trailer is normally held i a given position upon thelsupport 559 by meansof a bolt 560 which passes slidably through three eyes, l l V l I controlled by the primary trailer are fixed upon the boat '500- and the third of which,.562, is arranged between and in aline ment with the other two and is fixed upon the secondary trailer- 502. Whenthe second'ary trailer is in this position its cable 506 s arranged in acoil upon the boat 500.

For automatically severing the towing cable 505 of theprimary trailer 501 at a point near" its inner end, and for simultaneously. releasing: the secondary trailer 502 and rendering it operative as a result of a short circuit or a break in the circuit 536,

v) a hollow cylinder 570 is fixed upon the boat- 500 and is-provided with a piston'rod 571 extending s. jecting in opposite directions therefrom. One end'of this rod is rigidly securedto the ohter end of the bolt 560, and rigidly secured to the other end of-this rod is-a knife 572 having a shar edge normally spaced outwardly from an" facing the towing cab-lo 5050f the primary trailer 501 and arranged to be moved inwardly with the rod 571 in such a path as tosever the cable 505. piston is arranged to reciprocate in the cylinder 570and is fixedly secured to the piston rod 571. This piston is normallv held in its innermost .position as shown in Fig.2? by means of a compressed spiral spring 576 arranged in the cylinder 570.

The outward movement of the iston 575 is limited by means of a collars? adjustabily 581 and a crossbar 582-O7f insulating material which is terminally connected pi-votally .to the two arms' The two arms 580 and '58 1 are arranged to swing respectively about the two fixed "terminals 555 and 556 and to be'swung from the operative position shown in full lines in Fig. 23 to the other 0 rative v ositionshown. in dotted lines in ig. 23 v means of a le'ver,583 which is pivotally connected to the crossbar 582and the inner end oi which is prowi-ded with an elongated slot 584 the walls 0% which slidably's u'rround a'fi'ered pivot 585. The outer end of the lever 583- is pi otally connected to one end of a connecting rod 586 the other end of which is pivotallyyconnected to the outer endof a lug-587 which is rigidly secured to the piston rod 571. i

For control-ling the piston 575-. a tank 590' or other source of compressed. air .is provided and. arranged to communicatewith the inner end or the cylinder 570 through pipe 591 contrc'illed'by a normally cldsed piston valve 592 or other suitable-valve controlled by fixed electromagnet 593. The electromagnet 593-isin a normally-open circuit In: eluding a battery 595', a; fixed terminal 596, and a pivoted armature 597 which is arranged to swing into and out of engagement idably therethrough and pro ma. Flf1. 23,, with fore described sound receivers arranged to be operated as a sound transmitter,

nae-5345 with the fixed Contact 596 and. to be norw -mally held out of engagement therewith against the action of a spiral spring598 by circ'u-itedpthe battery 527 would cease to energize the electrouiagnet 545 and conse-.

quently the armature 597. 'would. be perniittedtorlosr'the circuit through the elect-romagnet 593 thus opening the valve 592 and permitting the compressed air from the tank 590 to force the piston 575 outwardly tothe limit of its stroke. This movement of the piston 575 would cause "the piston rod of either trailer 501 or 502 and the circuits controlled thine-by from the boa-t 500 with-- out operating a distant submarine transmitter, the boat 500 maybe provided with any suitable means for generating submarine compressinal waves having a frequency the same as that to which thetrailers are tuned to respond, and: having an amplitude about the same as would be the amplitude at the traiilers of compressional submarine oscillatiaons when received from a distant station wheil the boat 500' is at approximately the ma'xin'rinm distance it is desired to harve it proceed from the'stati'on. For instance-the boat 500' any one of the hereinbethe transmitter 105 3-06 shown in Fig.

23 for this purpose being the same in construction and- .orrange nent as the hereinbefore described receiver shown in Fig. 14:, except that instead-of having its circuit 133, 134 arrangedto-be energized as a result-of the vibration of the primary diaphragm- 306,

this circuit is arranged-to have electrical oscillations. of the desired frequency set up therein as a result of the action of an electrical oscillator or vibrator of any well known or suitable construction. In the formshown in- Fig. 23 this circuit 133, 134 is arto he energized by means of an electricaloscillator 600 of well known construcbe provided, as shown in tion comprising a tuning fork 601, a telephone transmitter button or microphone 602,

and an electromagnet 603. The tuning fork" 601is so selected that the natural frequency .of the vibration of its prongs is exactly the same as the frequency to which the trailers 501 and 502 are tuned, and the microphone- 262 is rigidly secured to the shank of the' tuning fork in such a manner that as the tuning fork vibrates, the resistance of the microphone will be periodically varied accordingly. The electromagnet 603-is fixed between the prongs of the tuning fork and .is in a circuit which includes a battery-604 and the microphone 602.; The circuit '133,

l34iis' shunted around the microphone and forms a derived circuit in which ismserted acondenser 605 and a variable impedance In the operation of the transmission sys temshown in- Fig. 23, the tuning fork 601:

I having. been once set into vibration by strik'-- ingone of its prongs will be caused to con tinue to vibrate in ts natural frequency by j the action of the battery 604 acting through themicrophone 602, and the impedance 606 having been roperly adjusted, continuous I, electrical osci lations having the same f requencyas the natural frequency of vibration of the tuning fork and having a constant amplitude of suitable magnitude will be set compressional waves which comprises a plu-' ra'lit'yof vibratory elements arranged to respond in succession'to the action of com- =pressional waves and conjointly operative' to as 'there' are elements-unless the elements have the same natural fr uencyof vibration or are so connected toget erasto be comsetup electrical oscillations successively ina plurality of electrically coupled circuits wherein the oscillations are amplified and act ultimately tocontrol a plurality 'of receivingidev ces. i For yeryvibrating system of one element thereis one frequency of vibration to which it will respond more readily than to an other unless the system is heavily dampe If the system contains more than one element which may vibrate there will be in general as many difierent periods of free vibrations pelled to vibrate in unison.- The less closely or rigidly the elements are coupled or con- 'nected together-the easier ibisfor any one element to assert its own characteristic. This determined e perimen l! tively easy to duplicatetheresultsl formed in the pipe.

is true in mechanics and electricity as well as in sound, one of the most common exam-' ples being found in electrical transformers, where with magnetism as the connectinglink betweentwo coils ofwire, the connection is made closer as the'magnetic reluctance is made less, either by bringing the coils-closer .to each other or by inserting an iron core be'-.

tween the coils, or by doing both. In any case the more nearly all of the vibrating elements are tuned to respond to'the same fro- 'quency, the more sensitive the system will be" to respond to the frequency to which it is tuned,and the less. likely theisystmiwm Be a.

torespond to any other frequenc The system provided by this vention-sinclndes as hereinbefore described, one oi,more primary diaphragms arranged to receive compressional submarine vwaves and" to act through-"a resonator or confined column of air to set up vibrations in asecondaryjdiaphragm which is -'arranged to actuate a generator of' electrical oscillations. "The 'dia phragms and the enclosed column of air are"- so proportioned and arranged as to have the same natural frequency of vibration "when in their operative, positions. It is not. suflicient to time each of these elements by itself and then assemble the elements, as when the elements are assembled each element I reacts upon the others, and allowance must'be'made forthis' as determined by experimental trial under actual working conditions. After the, proper proportions of each partand a' 'suitable arrangement of the parts have been thus y it is""c ompara- The mperature compensating device same standard pite temperature ranges. In th 'edevice 170-196 is shown applied 't'o alyertieal organ pipe 700 of well known construction""- rovid' ed with the'us'ual lip 701 and having an a ownin Figs; .9fand'j 11 fmijght be applied to keep orgpn pipes 'ini'tune to the nnder -widely varying open upper'end and havin a tapQrdLl wer end provided with an in at 702 for com ressed air.- Thespiin dle-17 is placed across the upper open end of the pi to'loc'ate the valve176 at the crest-oft e soiind wave compensatorin 24 is the'same as that shown in Figs. 9 and 11 'andtheoperation is the same. i l

Only a few of themany forms in which this invention-maybe embodied have been described herein, and it is toflbe understood that the invention is not limited to, any specificc'onstruction but might be applied in various-forms without departing from the its The construction'j of the spirit of the invention or the scope of the appended claims. 7

Havin thus fully described my invention, what I c aim is: r

1. A receiver for compressional waves 

